: the owners manual calls for regular 30w castrol gtx, i understand. I am using a trans i pulled out of a '76 '02 that i bought as a parts car. i went to change the existing oil before putting the gearbox in my project car and found the gearbox had very little oil. The gearbox worked fine when i drove the car prior cannibalizing it. What weight oil do i use? I saw somewhere that somebody suggest atf.

If it's any use, I used Mobil synthetic gear oil when I did a 5 speed conversion on my 2002 and it seems to work well. Have just put the same oil on my '89 325i and am hoping it will cure the poor gear change in cold weather,